645273751 has 8 divisors (see below), whose sum is σ = 668162880. Its totient is φ = 622427232.

The previous prime is 645273721. The next prime is 645273767. The reversal of 645273751 is 157372546.

645273751 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 645273751 - 2¹³ = 645265559 is a prime.

It is a super-2 number, since 2×645273751² = 832756427459220002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645273701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21901 + ... + 42073.

It is an arithmetic number, because the mean of its divisors is an integer number (83520360).

Almost surely, 2^645273751 is an apocalyptic number.

645273751 is a deficient number, since it is larger than the sum of its proper divisors (22889129).

645273751 is a wasteful number, since it uses less digits than its factorization.

645273751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21305.

The product of its digits is 176400, while the sum is 40.

The square root of 645273751 is about 25402.2390942216. The cubic root of 645273751 is about 864.1344772214.

The spelling of 645273751 in words is "six hundred forty-five million, two hundred seventy-three thousand, seven hundred fifty-one".